Method of tanning sole leather



Jan. 20, 1931. c. KANNEL 31,789,629

METHOD OF TANNING SOLE LEATHER Filed Aiaril 4, 192a BY v r WWW/W Patented Jan. 20, 1931 PATENT OFFICE 1 CHARLES KANNEL, F BROOKLYN, NEW YORK METHOD OF TANNING SOLE LEATHER,

Application filed April 4, 1928. Serial No. 267,153.

} v The present invention relates to a method of tanning leather. It is already well known to tan leather in a vacuum as for instance according to the I 5 method of Nance of France. But, the performance of the Nance method requires the L building of relatively large stationary vessels made of copper, brass or concrete which must be equipped with heating means and means for supplying compressed air. According to the Nance method it takes considerable time tocomplete the tanning.

The object of my invention is to simplify the method so that comparatively simple means can be used for carrying out the method and whereby the latter can be completed in the shortest possible time. My new process consists in that the raw skins are first limed, for a short period of time, then on i removal of the hair and flesh are cleaned, then, without, as hitherto, firstdecalcifying, are placed into a bathcomposed of about 100 quarts of water, 250 grams of potassium chromate, 200 grams boracic acid, 250 grams sulphuric acid or similarly acting acids, such as 180 grams of formic or 210 grams of butyric acid, to which may be added about 50 grams of glycerine. In this bath the skins are kept for about 16 to 24 hours.

By treatment in such bath the skins are rendered insensitive against the highly concentrated tanning substances to be used in the process and on the other hand receptive i ot said substances.

On the removal of said skins from said ath, they are placed in a suitably reinforced drum containing any kind of tanning solument of the skins in said drum the latter is maintained in motion and under the action of suction, the air therein rarified and the injurious gases produced during the tanning \process and which render the leather brittle are withdrawn.

Bymy new method the tanning process can be completed in a period of less than 24 hours and the product derived therefrom is of the best quality, such as produced by the hitherto used very complicated processes.

Apart from that, there is a great saving tion of 1244? Baum. During the treat-- lasting treatments are lost owing to the carbonic acid formed.

A great advantage of my method is thatany available tanning vessel can be employed for carrying out the same.

To make my invention more clear I have illustrated the same in the accompanying drawing in which similar reference char-.

'acters denote corresponding parts and in which Fig. 1 is a longitudinal section of a common wooden barrel with the means for evacuting the same and Fig. 2 is a cross section of a slightly modified construction.

- In the drawing according to Fig. 1 an ordiv nary wooden or wood lined suitably reinforced barrel 10 is mounted on a longitudinally perforated shaft 11 which is revolved from a suitable source of power through belt and pulley 12, 13 respectively. vThe 7 shaft is rotatively supported in a suitable frame 14 and one end thereof is connected to a vacuum pum -16 by a hose or pipe 16 by means of a suitable joint 16' so that saidshaft 11 may be rotated while connected to said pump.

In Fig. 2 the shaft 11 of the barrel 10 is adapted to receive oscillatory motion. To this end the shaft may be provided at its outer ends with gears 17 each having a few teeth 18 which when the shaft is rotated, will alternately mesh with arallel stationary racks 19, 20 that according to the present example are shown to be integral parts of the frame. 5

The movement imparted to the vessel either rotary or oscillatory expedites the tanning process in that the friction caused between the pieces of leather or hides contained in the vessel produce the heat necessary for the process and which causes the opening of the pores in said material so that the tanning substances can effectively pass into the material.

What I claim is 1. In a process of tanning sole leather or the like the step of treating the same in a rotating condition in a tanning substance under a constantly maintained vacuum.

2. A method of tanning sole leather coning in treating limed cleaned skins in a th, to which potassium chromate has been ded and then in a rotating condition in a I 'ng substance under a constantly mainined vacuum. 3. In the process of tanning leather raply comprismg the step of treating the limed 'ns in a bath to which potassium chromate, racic acid, another non-oxidizing acid, (1 glycerine, have been added. 4. A method of tannin leather including 0 steps of placing the limed cleaned skins a. bath to which potassium chromate, bocic acid, another non-oxidizing acid and ycerine have been added, then treating em in a rotating condition drum c0ntain g a tanning' solution, agitating said skins erein and at the same time continuously intaining a vacuum for withdrawing the formed by the chemical reaction. 5. A method of tanning leather including steps of pretreating the'limed skins in olution to which potassium chromate and i cerine have been added and then treating em in a tanning solution and a constantly :intained vacuum. 1 6. A method of tanning leather including e ste s of pretreating the limed skins in acid bath and then treating them in a ning solution under a constantly mainined vacuum as they form. 7. In the process of-tanning leather the p of retreatin the limed'cleaned skins a bat contaimng the reaction products a mixture of potassium chromate, boracic.

id, lycerine and sulphuric acid and water. 8 fn the process of tanning leather.the -ps of pretreating the limed cleaned skins r 16 to 24 hours in a bath containingthe action products. of a mixture of substanlly 250 grams of tassium chromate, 200 ams of boracic aci 250 grams of sulphuric id and grams of glycerine to every 100 arts of water;

sllbjectin said treated skins to a tanning solution or approximately 24 hours under a constantly maintained vacuum for withdrawing as formed the gases caused by the tanning reaction.

12. A bath for use in the process of tanning leather comprising the reaction products of a mixture of potassium chromate,

boracic acid, sulphuric acid and glycerine in water. 7

13. A pretreatin bath for use in the process of tanning. leat er comprising the reaction products of a mixture in the approxiwithdrawing the gases formed by the chemi- I cal reaction as they form. a

' 16. A bath for use in the process of tanning leather comprising the reaction products of a mixture of potassium chromate,

boracic acid, butyric acid and glycerine in water.

17. A bath for use in the process of tan- A ning leather comprising the reaction products of a mixture of potassium chromate,

boracic acid, formic acid and glycerine. in

water.

In testimony whereof I aflix mv si nature. CHARLES KA NEL.

9. In the process of tannin leather the p of pretreating the cleaned limed skins r 16 to 24 hours in a bath to which subntially 250 grams of potassium chromate, 0 grams of boracic acid, 210 grams butyric id and 50 grams of glycerine to substan- (111% every quarts of water have been e p 10. In the process of tanning leather the ep of pretreating the cleaned limed skins r 16 to 24 hours in a bath to which subantially 250 grams of potassium chromate,

ll grams of boracic acid, 180 grams of 

